ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

nov. 8. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F I. 1. emelet, Schay terem

Dáinel Varjas and Gergő Pintér (IFW Dresden and BME Elméleti Fizika
Tanszék):
Stability of Weyl node merging processes under symmetry constraints

Weyl semimetals are materials with topologically protected point-like
degeneracies (Weyl nodes) in their band structures. When tuning external
parameters, such as magnetic field or strain, isolated nodes move in
momentum space, but small perturbations cannot gap them out. Changes in the
number of Weyl nodes occur through merging processes, usually involving a
pair of oppositely charged nodes. More complicated processes involving
multiple Weyl nodes are also possible, but they typically require fine
tuning and are thus less stable. In this work, we use
singularity-theoretical tools to study how symmetries affect the allowed
merging processes and their stability, focusing on the combination of a
two-fold rotation and time-reversal (C2T) symmetry. We find in this case
that, counter-intuitively, processes involving a merging of three nodes are
more generic than processes involving only two nodes. Our work suggests
that multi-Weyl-merging may be observed in a large variety of quantum
materials, and we discuss MoTe2, SrSi2, and bilayer graphene as potential
candidates.

Reference: arXiv:2403.08518 (PRL in press)

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor